Application of mud-laden fluids to oil or gas wells



Patented Feb. 19, 1935 vPATENT OFFICE APPLICATION. OF MUD-LADEN FLUIDSTO OIL 08 GAS WELLS Phillip E. Harth, St. Louis, Mo..

tional Pigments & Chemical assignor to Na- Company, St.

Louis, Mo., a corporation of Missouri I No Drawing. Application October10, 1929,

Serial No. 398,818

g 20 Claims.

This invention relates to mud-laden fluids and more particularly totheir application to oil or gas wells. This application is acontinuation of application Serial No. 71,855, filed November 27, 1925,as to common subject matter.

A mud-laden fluid is used in the drilling or boring or for the controlof oil or gas wells. In rotary drilling the fluid is introduced throughthe drill stem to the bit and there issues to rise in the bore-hole,thereby performing; the function of a lubricant and also as a conductingfluid to carry oii the cuttings. Such a fluid also performs the functionof mudding off, that is Walling the bore-hole, as well as holding downpressures by its weight.

In the Stroud Patent No. 1,575,945, March 9, 1926, is described theapplication of a mud-laden fluid to oil or gas wells, in which thedensity of the fluid is controlled by the addition of a heavysuspendable substance such as barytes (barium sulphate), ferric oxide(F8203) or plumbic oxide (PbO), the barytes or iron oxide or lead oxidebeing used either alone as a suspendable base or in connection withordinary mud as obtainable at the well, in order to obtain a mud-ladenfluid or suspension having the required specific gravity at the desiredviscosity.

While it is not difiicult to secure a suspension of the finely dividedparticles or suspendable bases found in the ordinary mud as used inwells before the advent of the subject-matter of the Strand patent, andeven of the pigment bases barytes, etc., referred to and employed asdescribed in the Stroud patent, the problem of keeping them insuspension is more difl'icult. It is important that the suspendable basebe main tained in suspension in an oil well; for if it shouldprecipitate or settle out, then the drilling operations are interferedwith and the tools are liable to stick or become frozen especially whenthe drilling operations are interrupted. Such settling interferes withthe landing or setting of easing, oftentimes necessitating drilling outof the settled material. Settling also oftentimes prevents theresumption of circulation, as it is impossible to dislodge the settledmaterial by means of the pressure applied to the fluid by the pumps.Furthermore, settling interferes with the continuous flow to all partsof the bore-hole and causes some of the fluid in the column to be oflower specific gravity than in other parts of the column so that it maynot perform its function of mudding olf the bore-hole and holding downpressures. Furthermore, any settled mud, clay, barytes, or other finelydivided heavy material is difiicult to remove should it be founddesirable or necessary to do so. Settling also increases pumpingdifficulties and the cost of maintenance.

One of the objects of this invention, therefore, is to provide amud-laden fluid for oil or gas wells which not only has the heretoforedescribed properties and characteristics desired and necessary in orderto adapt it for its intended uses, but in which the suspendable basewill also be maintained practically indefinitely in a state ofsuspension.

Another object is to provide a process or method of applying such amud-laden fluid to the boring or controllingof oil or gas wells.

Further objects will appear from the detail description in which will bedescribed an illustrative practical embodiment of this invention; itwill, however, be understood that this invention is susceptible ofvarious other embodiments.

In accordance with an embodiment of this in vention, the mud-laden fluidcomprises what is I herein referred to descriptively as a suspendablebase, composed of a suitably finely divided suspendable material; thesuspension or suspendable base has combined therewith or added theretowhat is believed to be and is hereinafter referred to descriptively as aconcentrated colloidal suspending agent, and which is adapted to keepthe suspendable base practically indefinitely in suspension in'asuitable liquid such as water, when added thereto to form the mud-ladenfluid. In accordance with this invention the mud-laden or drilling fluidcontains or employs a concentrated colloidal clay such as Bentonite andsuch a fluid is employed in the process of boring or controlling of oilor gas wells.

The suspendable base or suspended material may be any of the variousmaterials adapted for distribution in the dispersion medium such aswater. It may be any of the finely divided materials heretofore referredto, including clay and the various pigment bases, preferably of highspecific gravity. A suitable base is barytes, which even in its rawstate is very pure, the barium sulphate content running as high asninety-eight percent. Other suitable and similar bases are ferric oxide(F6203) or red pigment or plumbic oxide (PbO) or litharge. All of thesecan be suspended in ordinary drilling mud as found at the wells.

The concentrated colloidal suspending agent may be a suitable oneadapted for the particular suspendable base or disperse phase and thedispersion medium. A-suspending agent which I have found particularlyuseful in keeping the suspendable bases referred to above insuspensionin water, is a suitable concentrated colloidal clay known as Bentonite.A typical average sample (after dressing of the crude product) of such aconcentrated colloidal clay has thefollowing chemical analysis:

The physical analysis of such a typical sample 25 is as follows:

Diameter in milli- Per Division Name meters cent 30 1 Medium sand l. 0.None Sand 0.5 0. 15 0. 04 Fine sand 0. l5 0. 075 0. 41 Very fine sand0.075 -0. 033 2.02 0.033 0. 008 3. 86 Fine si1t.- 0.008 0.003 2. 23 Veryfine silt 0.003 -0. 0015 17. 62 Clay, finer than 0015- 73. 82

As an example of the practice of this invention, if it is desired toobtain a mud-laden fluid in which the suspendable base or disperse phaseis barytes and the dispersion medium water, the

40 concentrated colloidal clay and barytes are mixed dry in theproportion of from 2 to 5% of the colloidal clay and 98 to 95% ofbarytes. By incorporating this mixture in water in the desiredproportion a mud-laden fluid will be formed in 45 which the barytes willremain in suspension practically indefinitely.

It is found that by the employment of the concentrated colloidal clay inthe manner described, it will act as a suspending agent so as 50 to keepthe suspendable base practically indefinitely in suspension in water orin the mud as found at oil wells. It can be made of the requiredspecific gravity to give the desired weight, and still be foundsufiiciently thick or viscous in 55 order to hold the cuttings insuspension, while still being of sufilciently low viscosity so as toenable it to be pumped and so as to enable the cuttings to settle in asettling ditch. Even when barytes is used as a suspendable base, a mudof 60 any desired specific gravity can be obtained having the desiredphysical state. Not only can a mud be made using simply barytes or oneof the iron or lead oxides, but the mud so formed can be cut down withordinary mud as obtainable 65 at the well, so as to obtain the desiredmud-laden fluid of the desired specific gravity and of the desiredviscosity.

Moreover some of the advantageous features of this invention may beobtained by using ordinary clay together with the concentratedsuspending agent. By, however, employing only a small percentage of theconcentrated colloidal clay as a suspending agent when barytes alone isused, the mud will not be stained sufliciently to detract from its whitecolor. Accordingly, a mud-laden fluid containing barytes and a smallpercentage of the colloidal clay will be white and will, therefore,serve to readily indicate the presence of petroleum.

It will, therefore, be seen that in accordance with the describedembodiments of this invention there is produced a mud-laden or drillingfluid containing a concentrated colloidal suspending agent such as thecolloidal clay of the character described. The suspendable base of .themudladen fluid is kept in suspension practically indefinitely by theaddition of a small percentage of the concentrated suspending agent suchas the concentrated colloidal clay heretofore described, while thedensity can be controlled by the addition or presence of a heavysuspendable substance. Accordingly in oil wells the mud-laden fluid willremain in the right condition in that the base thereof is kept insuspension, even if the drilling operations are interrupted for anextended length of time. While clay laden drilling fluids containcolloidal material, and while the specific gravity of such clay ladenfluids has been substantially increased by the addition of barytes, etc;the proportion or concentration of colloidal material is relativelysmall, thereby imposing limits on the colloidal material which adrilling fluid may contain before the limiting viscosity is reached. By,however, adding a concentrated colloidal suspending agent asdistinguished from a dilute one to the drilling fluid, it is onlynecessary to add a small percentage of the suspending agent in order tosecure the desired results.

The specific concentrated colloidal suspending agent Bentonite referredto and described by its chemical and physical characteristics, isparticularlyuseful and valuable in maintaining the mud-laden fluid in astate of suspension at the bottom of a deep Well. It also produces amudladen fluid having the desired properties and characteristicsheretofore described. It is a material which after removal of its sandyimpurities, usually contains 75% or more of the crystalline claylikeminerals, montmorillonite beidellite, and which is now commonlyclassified and known as a Bentonite. It has a strong aflinity for water,absorbing many times its weight or volume of water with a consequentincrease in volume and with the formation of a slippery, plastic,gelatinous mass that resembles soft soap and which when agitated withmore water, results in a permanent suspension. Some authorities haveclassified Bentonite as emulsoid colloids particularly because of thischaracteristic of water absorption and swelling. Other suitableconcentrated colloidal suspending agents and more particularly emulsoidcolloids may, however, be employed to attain some or all of the objectsand advantageous features of this invention. Examples of these arestarch, gelatin, sodium silicate solutions, gum tragacanth, agar, caseinglue, soybean glue, albumin, and other similar substances, all of whichact as suspending agents upon the bases which may be used in mud-ladenfluids.

It is to be understood that while a theory of operation has beenadvanced, it is not the only or necessary one'but has only been advancedto facilitate the disclosure. It is understood, however, that thisinvention is not limited to any theory of operation or action. It isfurther obvious that various changes may be made in the details withoutdeparting from the spirit of this invention; it is, therefore, to beunderstood that this invention is not to be limited to the speciflcdetails described.

Having thus described the invention, what is claimed is:

1. A mud-laden fluid for oil or gas wells comprising a suspensible baseand an added concentrated colloidal suspending agent therefor.

2. A mud-laden fluid for oil or gas wells comprising a suspendable baseand a small percentage of an added concentrated colloidal suspendingagent therefor.

3. A mud-laden or drilling fluid for oil or gas wells containing aconcentrated colloidal clay of the character described.

4. A mud-laden fluid for oil or gas wells comprising 98-95% of asuspendable base and 2%-5% of a concentrated colloidal clay.

5. A mud-laden fluid for oil or gas wells comprising a suspendable basehaving a specific gravity substantially in excess of that of clay and anadded concentrated colloidal suspending agent for said base.

6. A mud-laden fluid for oil or gas wells comprising a pigment basesuspensoid and an added concentrated colloidal suspending agenttherefor.

7. A mud-laden fluid for oil or gas wells comprising barytes and anadded concentrated colloidal suspending agent therefor.

8. A mud-laden fluid for oil or gas wells comprising barytes and aconcentrated colloidal clay.

9. A mud-laden fluid for oil or gas wells comprising barytes and 2%-5%of a concentrated colloidal clay.

10. A mud-laden or drilling fluid for oil or gas wells containingBentonite.

11. A mud-laden fluid for oil or gas wells comprising a suspendable baseand a small percentage of Bentonite.

12. A mud-laden fluid for oil or gas wells containing barytes andBentonite.

13. In the art of boring or controlling oil or gas wells, the processcomprising introducing 3 into the well a mud-laden fluid containing asuspendable base and adding thereto a concentrated colloidal suspendingagent therefor. 14. In the art of boring or controlling oil or gaswells. the process comprising introducing into the well a mud-ladenfluid containing a suspendable base and keeping the base in suspensionby the addition of a concentrated colloidal suspending agent therefor.

15. In the art of boring or controlling oil or gas wells, the processcomprising introducing into the well a mud-laden fluid, controlling thedensity thereof by the addition of a heavy suspendable base and keepingthe heavy base in suspension by the addition of a concentrated colloidalsuspending agent therefor.

.16. In the art of'borlng or controlling oil or gas wells, the processcomprising introducing into the well a mud-laden or drilling fluidcontaining a concentrated colloidal clay of the character described.

17. In the art of boring or controlling oil or I gas wells, the processcomprising introducing into the well a mud-laden fluid, controlling thedensity thereof by the addition of barytes and keeping the barytes insuspension by the addition of a concentrated colloidal clay.

18. In the art of boring or controlling oil or gas wells, the processcomprising introducing into the well a mud-laden fluid and aconcentrated colloidal suspending agent adapted to keep the particles ofthe mud-laden fluid in suspension.

19. In the art of boring or controlling oil or gas wells, the processcomprising introducing into the well a mud-laden or drilling fluidcontaining Bentonite.

20. In the art of boring or controlling oil or gas wells, the processcomprising introducing into the well a mud-laden fluid the base of whichis composed of barytes and Bentonite.

PHIILIP E. HAR'I'H.

Disclaimer 1,991,637.-Ph'illip E. Harth, St. Louis, Mo; ArrLIoA'moN orMun- T0 01L OR Gas WELLS. Patent dated Feb. 19, 1935. Disclaim dilil glit'l i H 948, by the mventor, and the assignee, National Lead Company. pi

ere y enter this disclaimer to the followin arts of the s e From thespecification all mud-laden or dr' irig fluids excep gflfi gg fil l comosed of o d a l p re pnman'ly collolidal suspei'ldlillllagry wager c anldsi, but coltiltamtiing also an added c0ncentrated a en or an a econcen ate g1] asigrlgremtahfter adiltfinauy defined; colloidal clay ora bentonite,

m e s cc cation all concentrated colloidal sus endin a en l concentratedcoll oidal' clay or a hen tonite both as hereina iter ad ditl mail lydzli ii ed starch, gum trag'acanth, and agar; From the specification allconcentrated colloidal clays and all bentonites except such which, afterthe drcsslng of the crude product, that is, after removal of its sandyimp'uritles, contains predominantly mon tmorillonite which imparts thecharacteristics of strong aifimty for water, absorbing many times itsweight or volume of water with a consequent increase m volume and withthe formation of a slippery plastic gelatmous mass that resembles softsoap and which when agitated with more water results in a permanentsuspension' From the s ecification the following a pearing on page 2,right-hand column hnes 62 to 64 me usive: gelatin, sodium si 'eatesolutions, casein glue soybean glue d lb in; -7 7 From the scope of eachand evefiv claim all mud-laden or dr' ing fluids except such as areprimarily composed of or inary water-clay muds, but containing also anadded concentrated colloidal suspending agent, or an added concentratedcolloidal clay or a bentonite, as designated in the respective claims,all as heretofore additionally defined;

From the scope of each and every one of claims l, 2, 5, 6, 7, 13, 14,15, and 18, all concentrated colloidal suspending agents except aconcentratedcolloidal clay or a bentonite both as heretoforeadditionally defined, starch, gum tragacanth and agar;

From the scope of each and every one of claims 4, 5, 6, and 15, each andevery designated suspendablebase and pigment base except barytes or ironoxide;

From the scope of each and all of claims 3, 4, 8, 9, 16, and 17, allconcentrated colloidal clays except such which, after the dressing ofthe crude product, thatus, after removal of its sandy impurities,contains predominantly montmorillomte Whlch imparts the characteristicsof strong aflinity for water, absorbing many times its weight or volumeof water with a consequent increase in volume and with the forma tion ofa sli pery, plastic, gelatinous mass that resembles soft soap and whichwhen agitated wi't more water, results in a permanent suspension;

From the scope of each and every one of dams 10, 11, 12, 19, and 20, allb'entonites, except such which, after the dressing of the crude product,that 1s, aftermmoval of its sandy impurities, contains predomlnantlymontmorillomte wh1ch 1mparts the characteristics of strong aflinity forwater, absorbing many times its weight or volume of water with aconsequent increase m volume and with the formation of a slip ery,plastic, gelatinous mass that resembles soft soap and which whenagitated with more water, results in a permanent suspension.

[Oflicial Gazette May 11, 1.948.]

DISCLAIMER 1,991,637.-Phill11p E. Harth,-. St. Louis, Mo. APPLICATION orMUD-LADEN Fnoms 'ro OIL 0R Gas WELLS. Patent dated Feb. 19, 1935.Disclaimer filed Nov. 26, 1946, by the inventor and-the assignee,National Lead Company.

Hereby disclaim:

From the specification viz., page 1, second column, lines 47 and 48, andfrom the scope of each and every one of the claims thereof, red pigmentor plumbic oxide (PbO) or litharge;

Fromthe specification viz., page 2, second column, lines 62 and 63, andfrom the scope'of each and every one of the claims thereof, sodiumsilicate solutions;

From the scope of each and every one of claims 1, 2, 5, 6, 7, 13, 14,15, and 18, all concentrated colloidal suspending agents, except such aswere properly described as emulsoid colloids, viz., those having thecharacteristics of water absorption and swelling with a consequentincrease in volume, and which emulsoid colloids are of a classconsisting of bentonite, starch, gelatin, gum tragacanth, agar, caseinglue,

soybean glue and albumin;

From the'scope of each and every one of claims 3, 4, 8, 9, 16, and 17,all concentrated colloidal clays except such concentrated colloidalclaysa typical average sample of which has the following analyses:

Percent Silica, (SiO 57. 98 Ferrous oxide, (FeO) 0. 12 Ferric oxide, (FeO 3. 8O Alumina, (A1 0 22. 46 Lime, (CaO) 1. 92 Magnesia, (MgO) 3. 24Soda and potash, (N a O, and K 0) 1. 35 Sulphur trioxide, (S0 0. 75 Losson ignition, (H 0, 00 Org.) 7. 93

. e9. 45 Calcium carbonate, (CaCO calculated 3. 14 Sodium sulphate, (NaSOQ, calculated '1. 34 Division I Name Diameter in mill' eters Percent 1Medium sand 4 1. 0 O. 5 None 2 Sand 0. 5 O. 15 0. 04

3 Fine sand O. 15 0. 075 O. 41

4 Very fine sand 0. 075 0. 033 2. O2

5 Silt 0. 033 O. 008 3. 86

6 Fine silt O. 008 O. 003 2. 23

7 Very fine silt 0. 003 O. 0015 17. 62

8 Clay, finer than 0015- 73. 82

and which concentrated colloidal clays have the physical properties andcharacteristics as described, viz., of keeping the described suspendablebases of mud-laden Efluids for the drilling of oil or gas wells insuspension practically indefinitely and of walling the bore hole; and

From the scope of each and every one of claims 10, 11, 12, 19, and 20all bentonites except such as were properly described as emulsoidcolloids, viz., those having the characteristics of water absorption andswelling with a consequent increase in volume.

[Ofiicial Gazette December 24, 1946.]

Disclaimer 1,991,637.--Phillip E. Harth, St. Louis, Mo. ArimoA'rioN orMUD-LA TO 01L ORGJlS WELLS. Patent dated Feb. 19, 1935. Disclaimer lildil d p i' i H i948, by 511118 inventor, and the assignee, National LeadCompany.

ere y enter t is disclaimer to the followin parts of the s ecification aFrom the specification all mud-laden or dr' ing fluids exce pt such asai p i' i iggsil ccgfiltggield I 1 sfporc(l11 nary wager-claynuldsl, butcontaining also an added concentrated s on ing a on or an a econcentrated an asFggremtal'lfter adzifiitlonauy (iffined; v colloidalclay or a bentonite,

m e s cc cation a concentrated colloidal sus endin a en concentrated cooidal clay or a bentonite both as hereina iter a ditimailly d ii ii edstare? trag'acfgith, andnagar; Y H

mm c spec cation a concentrated co oidal cla s and all bentoni suchwhich, aftenthe dressing of the crude product, that is, after removal ofi is i if impurities, contains predominantly mon tmorillonite whichimparts the characteristics of strong aflin ty for water, absorbing manytimes its weight or volume of water with a consequent increase in volumeand with the formation of a slippery plastic gelatinous mass thatresembles soft soap and which when agitated with more water results in apermanent suspension' From the s ecification the following a pearing onpag e 2; right-hand olum hnes 62 to 64 inc usive: gelatin, sodium si'cate solutions, casein glue soybean glue, and albumin;

' From the scope of each and ever claim all mud-laden or drilling fluidsexcept such as are primarily composed of or inary water-clay muds, butcontaining also an added concentrated colloidal suspending agent, or anadded concentrated colloidal clay or a bentonite, as designated in therespective claims, all as heretofore additionally defined;

From the scope of each and every one of claimsl, 2, 5, 6, 7, 13, 14, 15,and 18, all concentrated colloidal suspending agents except aconcentrated. colloidal clay or a bentonite both as heretoforeadditionally defined, starch, gum tragacanth and agar;

From the scope of each and every one of claims 4, 5, 6, and 15, each andevery designated suspendable base and pigment base except barytes oriron oxide;

From the scope of each and all .of claims 3, 4, 8, 9, 16, and 17, allconcentrated colloidal clays except such which, after the dressing ofthe crude product, that is,

after removal of its sandy impurities, contains predominantlymontmorillonite which im arts the characteristics of strong afiinity forwater, absorbing many times its weight or volume of water with aconsequent increase in volume and with the formation of a sli pery,plastic, gelatinous mass that resembles soft soap and which whenagitated wi't more water, results in a permanent suspension;

From the scope of each and every one of claims 10, 11, 12, 19, and 20,all b'enwnites, except such which, after the dressing of the crudeproduct, that is, after removal of its sandy impurities, containspredominantly montmorillonite which 1mparts the characteristics ofstrong affinity for water, absorbing many times its weight or volume ofwater with a consequent increase in volume and with the formation of aslip ery, plastic, gelatinous mass that resembles soft soap and whichwhen agitated wit more water, results in a permanent suspension.

0 75mm Gazette May 11, 1948.]

